让replaceScene更安全

如果可以这样的话 就不用担心用runWithScene还是replaceScene了. 可以省略getRunningScene判断.
Merge pull request #7712 from andyque/testLoadingBar

fixed loadingBar change direction affect position issue
[ci skip]
Merge pull request #7705 from zii/patch-1

让replaceScene更安全